Image Reading Device Tone Correction
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Solution Overview
Problem
Existing image reading devices face challenges in matching image densities and color tones between front and back sides of an original when using different reading units, particularly for color images, and existing solutions either fail to correct color tone differences or increase circuit scale and cost.
Innovation Solution
A method for image reading devices that involves using a monochrome reference original to correct the relative tone characteristics between reading units and a color reference original to adjust individual color components, thereby matching the input-output characteristics of both units to reduce differences in color and brightness between the front and back sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If image density matching is performed using a monochrome reference original, then the image densities of front and back sides are matched, but color tone differences between front and back sides cannot be sufficiently corrected
Solution Approach 1:
The correction process is segmented into two distinct stages: first correcting image density using a monochrome reference original, then correcting color tones using a color reference original. This segmentation allows each correction target to be addressed with appropriate correction data, resolving the contradiction between density matching and color tone matching.
Solution Approach 2:
The invention changes the correction parameters from单一的 density correction to dual-parameter correction including both density and color tone. By introducing color correction factors and gamma correction tables specific to color components, the system achieves both density matching and color tone matching simultaneously.
2Measurement precision
If gamma correction tables and color correction factors are determined to match color tones, then color tone differences are corrected, but circuit scale and cost are increased
Solution Approach 1:
The invention performs preliminary correction by determining gamma correction tables and color correction factors in advance using reference originals. These correction data are stored and applied during normal operation, eliminating the need for complex real-time calculation circuits and reducing device complexity while maintaining color tone matching capability.
Solution Approach 2:
The invention replaces complex mechanical correction systems with data-based correction methods. Instead of using complex hardware circuits to dynamically adjust color tones, the system uses pre-calculated correction factors and gamma tables stored in memory, substituting mechanical complexity with information processing.
Data Source
AI summary
Gains and offsets of the input-output characteristic of a second side reading unit are controlled so as to match input-output characteristic of a first side reading unit on the basis of image data of a gray chart read by the first side reading unit and the second side reading unit. Then, on the basis of image data of a color chart read by the first side reading unit and the second side reading unit, offsets of the input-output characteristic of the second side reading unit are controlled for individual color components such that differences between color read by the first side reading unit and color read by the second side reading unit are reduced.